Methods for assisting a driver of a motor vehicle are used, for example, to assist the driver during a parking process. It is also possible to assist the driver in maneuvering or in driving along narrow streets or dirt roads. To carry out this method, driver assistance systems are generally used, such as parking assistance systems.
Besides driver assistance systems that are used at low speeds, driver assistance systems are also known which assist the driver during driving at higher speeds. These include, for instance, lane-holding assistants or distance regulation from a preceding vehicle.
All driver assistance systems have in common that the surroundings of the vehicle have to be monitored. Distance sensors are usually used for this, which require different operating ranges, depending on the function for which they are being used. With the aid of distance sensors, for instance, objects that the vehicle is approaching are able to be detected.
In order to avoid a collision with an object when the vehicle is approaching the object, it is known, for example, from German Patent Document No. 102 37 714, that one may initiate an emergency braking process at a suitable time, when approaching an object, in order to avoid a collision with the object. Such an emergency braking process is particularly required if the vehicle is approaching the object at a speed that is too great for the distance from the object, and if there is the danger of a collision with the object in response to slow braking or even if the speed remains the same. In order not to initiate an emergency braking process suddenly, but to warn the driver of the vehicle first, it is known from German Patent Document No. 102 37 714 that one may carry out a warning braking process before the actual emergency braking process, which directs the driver's attention to the dangerous situation. By the use of the warning braking process, the driver is given the opportunity to get set for the dangerous situation and to prepare for a possible evasive maneuver. However, the disadvantage of this method is that the driver is warned only a very short time before the initiation of an emergency braking process, so that the driver is hardly given an opportunity of taking an action himself. He is only still able to react to the measures carried out by the driver assistance system.